The present invention relates to the discovery of a specific enzyme that has not been previously described, a phthalyl amidase, which readily removes the phthalyl moiety from phthalyl-containing amides. The present invention also relates to an organism isolated from natural sources that produces the enzyme, DNA compounds that encode the enzyme, and methods for producing and using the enzyme.
The phthalimido functional group is an important tool in organic synthesis because of the protection it provides against unwanted reactions. However, dephthalylation reactions generally require harsh conditions and often have low yields thereby limiting the situations in which phthalimido protection can be employed.
Removal of a phthalyl protecting group from a phthalyl amide can be accomplished chemically, Kukolja et al., Croatica Chemica Acta 49:779, 1977, but yields are variable especially with substrates that are unstable to harsh reaction conditions.
Certain enzymes have previously been found that could be used to remove benzoyl groups from benzoylated amino acids. Toyoura et al., Chem. Pharm. Bull. 7:789, 1959. These enzymes were specific for benzoyl groups and for the amino acid to which they were attached. Others have also reported enzymes that will hydrolyze phthalate esters. Kurane et al., Agric. Biol. Chem. 44:529, 1980. However, none of these enzymes have been shown to operate on phthalyl amides.
In contrast, the phthalyl amidase enzyme of this invention catalyzes removal of the phthalyl group from a wide variety of phthalyl-containing compounds with improved yields over processes known in the art, exhibits stereochemical selectivity, and eliminates the need for harsh conditions to remove the protecting group.